The present invention relates to electroplating processes for forming protective coatings on metal components, such as gas turbine engine components. In particular, the present invention relates to anode media used in electroplating processes, and methods for cleaning the anode media.
Components of a gas turbine engine are typically subjected to extreme temperatures and pressures during the course of operation, particularly in the high-pressure turbine stages of the turbine engine. To protect the turbine engine components from the extreme conditions, the components typically include metallic coatings that provide oxidation and/or corrosion resistance. The metallic coatings may also function as bond coats to adhere thermal barrier coatings to the substrates of the turbine engine components, and as particle matrices for retaining abrasive particles (e.g., cubic boron nitride (CBN) particles).
Electroplating processes are used to apply a variety of metallic coatings on turbine engine components, such as platinum and CBN-nickel coatings. A coating is typically formed by immersing a turbine engine component in a plating solution that contains metal salts of the intended coating. The anode of the electroplating system is also typically provided as anode media (e.g., pellets and shots) derived of the intended coating metal. An electrical current is then induced through the plating solution, which disassociates the metal salts to form charged metallic ions. The charged metallic ions then bond to the surfaces of the turbine engine component to form the desired coating.
As the charged metallic ions are consumed from the plating solution, the anode media are slowly dissolved to replenish the charged metallic ions in the plating solution. Thus, the continued effectiveness of an electroplating process is dependent on the emission of charged metallic ions from the anode media. However, a common issue with electroplating processes involves the formation of oxide and/or residue scale coatings on the surfaces of the anode media. These scale coatings block the emission of the charged metallic ions from the anode media, thereby reducing the rate at which the plating solution is replenished. Over multiple electroplating processes, the anode media becomes no longer effective at emitting charged metallic ions. At this point, the used anode media is typically discarded and replaced with fresh anode media, thereby increasing material costs for performing the electroplating processes. As such, there is an ongoing need to techniques for increasing the product lives of used anode media in electroplating systems.